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PSQ4W3ASTRON
MEASURING VAST DISTANCES
Question | Answer |
---|---|
Cosmos | the world or universe regarded as an orderly system |
Cosmological Redshift | elongating of light waves as they travel across an expanding universe; as the wavelength of light stretches, it becomes redder in color, thus the name cosmological redshift. |
Light year | distance that light travels in one Earth year; a light year is a unit of DISTANCE, about 10 trillion kilometers; we use light years to measure distance in the universe because the distances are so big. |
Magnitude | brightness of a star. |
Apparent magnitude | how bright a star seems to us on Earth. |
Absolute magnitude | of a star is how bright the star actually is. |
Parallax | apparent shift in the position of an object. |
Parsec | unit of distance equal to 3.26 light years. |
Alpha Centauri | other than the sun, the star closest to Earth; about 4 light years or 13 parsecs away. |